1. Technical Field
The present invention relates to a system including a client apparatus having a printing function, such as an inkjet printer or a laser printer, and a server apparatus connected to the client apparatus so as to communicate therewith over, for example, a network. In particular, the invention relates to a printing system for performing a billing process on a service supplied to a client apparatus, to a printing program, to a printing method, to a server apparatus, to a server apparatus program, to a printer, to a printing system program, and to a recording medium having these programs stored therein.
2. Related Art
In general, printers of an inkjet type (hereinafter, referred to as ‘inkjet printers’) are inexpensive and print high-quality images. Therefore, with the propagation of personal computers and digital cameras, the inkjet printers have come into widespread use for home as well as for office.
In general, in the inkjet printer, a movable body including an ink cartridge and a printing head which are integrally formed with each other is reciprocated on the right and left sides of a sheet feeding direction on a printing medium (a sheet), with liquid ink particles being discharged (jetted) from nozzles of the printing head in the shape of dots, to print predetermined characters or images on a printing sheet, thereby creating a desired printed matter. In addition, the carriage is provided with four color (yellow, magenta, cyan, and black) ink cartridges and four printing heads corresponding to the colors, which makes it possible to easily print a full color image having a mixed color of the four colors as well as a monochromatic image (further, light cyan and light magenta may be added to these four colors to realize six, seven, or eight colors).
However, the printing head indispensable for the inkjet printer has a plurality of nozzles, each having a diameter of 10 to 70 μm, which are linearly arranged at intervals of about several tens of micrometers and are also arranged in the printing direction in multiple columns. Therefore, the amount of ink discharged from some of the nozzles may be larger than a predetermined value due to, for example, manufacturing errors, or a variation in the discharge amount may occur in the same nozzle due to the residual quantity of ink or the viscosity thereof. As a result, dots having a predetermined size are not formed, which causes a defect in printing, which is called a ‘density irregularity’.
Therefore, in order to prevent the ‘density irregularity’, researches on hardware have been made to improve a technique for manufacturing the printing head or ink and to improve the design thereof. However, it is difficult to provide a printing head or ink having a low manufacturing cost and a high printing quality, but not generating the ‘density irregularity’ at all.
Thus, a technique for reducing the ‘density irregularity’ by improving software, such as the following printing control, in addition to by improving hardware has been proposed.
For example, JP-A-3-162977 discloses a method in which a density irregularity correcting unit corrects the density irregularity of a recording head with respect to a predetermined grayscale characteristic and a grayscale correcting unit corrects the grayscale characteristics of a predetermined unit of image recording elements of the recording head to absorb a variation in the amount of ink discharged from the recording head, thereby correcting the density irregularity.
However, in the method disclosed in JP-A-3-162977, each printer holds correction data (density irregularity table) of each of the image recording elements of the recording head. Therefore, the method has a problem in that it is difficult to use the optimum correction data coping with a variation in the characteristics of each printer, such as the deterioration of the printer with time.
Further, in order for each printer to hold the correction data, the printer needs to have a memory (a storage device) with a large capacity. In addition, in order to select the correction data most suitable for the deterioration of the printer with time, a large amount of information processing capacity (CPU power) is needed.
Accordingly, it is necessary to install a service system which manages the correction data for printing and provides correction data suitable for each printer, if necessary. However, in order to establish such a service system as a business, a system for performing a billing process for the service, such as a process of calculating a charge for the service and of notifying the charge, should be simultaneously developed with the service system.